Existing compensation structures for Electric Power Steering (EPS) systems often use torque loop compensation for an electric motor control system. In such existing EPS systems, a torque compensator, commonly a notch filter, is employed in the torque path to ensure that the system remains stable. However, application of a torque compensator may make the EPS system sensitive to disturbances or affect steering feel due to a phase lag, etc. The compensator may also cause the on-center feel to be less precise. The compensator may also have other side effects on the feel such as a road feel, a torque ripple, etc. Moreover, the frequency content of most of these issues typically corresponds to the frequencies of the compensator. Therefore, stability is achieved at a cost to steering feel.
By comparison, Hydraulic Power Steering (HPS) systems, which are functionally equivalent to EPS systems, do not have any torque path compensation, or the mechanical compensation that the HPS systems have at higher frequencies. The higher frequency compensation tends to be in the audible range (e.g., above 80 Hertz (Hz)), and therefore, does not adversely affect the lower frequencies (e.g., less than 10 Hz) corresponding to a steering feel range. Furthermore, in many ways (e.g., on-center feel, road feel, etc.), the HPS systems are still considered to have “premium feel.”